#3 No screwy finish
Screwy finishes are common in sports entertainment, the most famous of which being the Montreal Screwjob. Lesnar is not impervious to such booking misdemeanours, look at his 2015 Summer Slam match against The Undertaker.
With Styles beating Jinder Mahal to win the WWE Championship and be inserted into the match just weeks before Survivor Series, many speculated that a vengeful Mahal could cost Styles the match. Mahal interfering to help Lesnar win makes sense but it would have been an unnecessary and unwelcome booking decision.
Paul Heyman causing some sort of distraction or getting involved in any way shape or form would also taint victory for the Beast, but instead, Heyman sat on the outside of the ring holding the Universal title, stroking it like a James Bond villain strokes a cat.